1. Field of the Invention
The present invention relates to the field of security devices for computer magnetic tape reels, and in particular relates to the protection of information stored on reeled magnetic tape by means of a coded file protect ring.
2. Description of the Prior Art
The use of file protect rings in combination with magnetic tape reels for protection of the information stored on the tape is well known in the art. In its simplest form, the file protect ring, as shown in IBM Technical Disclosure Bulletin, Vol. 8, No. 10, March 1966, is an annular ring concentric with a central spindle opening of the tape reel, which annular ring is disposed within a corresponding annular groove defined with the tape reel. The ring thus allows the groove to be filled and the file protect ring forms part of the flush surface of the inside surface of the reel. The reel, with its flush surface as completed by the file protect ring, is then mounted on a tape recorder for reading or writing. With the file protect ring in place, a switch of the general types such as shown in Lee, "Erasure Prevention Control for Magnetic Tape Reels Having a Safety Ring to Prevent Insertion of a File Protect Ring", U.S. Pat. No. 3,688,057, bears against the flush surface of the file protect ring thereby assuming what is defined an actuating position to allow the tape to be erased or recorded upon. If the ring were not present, the switch assumes a nonactuated position and the tape cannot be written upon.
Clearly, in a simple device such as a gasket or ring disposed in a mating annular channel, any such file protect ring will fit any tape reel. Although such ring provides a means for preventing some operator errors, it provides no means for preventing intentional unauthorized erasure, reading or writing on the magnetic tape spooled on the reel.
What is needed then is some means whereby conventional magnetic tape reels which use such file protect rings, may be provided with some means for security or for selectively permitted erasure, reading and/or writing.